I was lucky enough to be on the Automattic team who developed the app, and got to interact with the internal Windows 8 team at Microsoft while doing so. Needless to say, it was both challenging and motivating, to say the least. Win 8 is pretty darn spiffy, which is saying a lot coming from a hardcore Mac and Linux user. :)

Oh, and yes, good habits die hard: the app is indeed open sourced, and released under the GPLv2. I wonder how many more OSS apps got featured not once, but twice by MS in their live worldwide demo? :)